Basement Sink Installation

I need to install a small sink in our basement. I plan to run the drain into the pipe shown here. The existing soil pipe serves one bathroom with two sinks, one of which gurgles, a toilet, tub, and shower. It does not serve any other areas of the house.

The sink will be located twenty pipe feet from the CL of the soil pipe against a to-be-built interior wall perpendicular to the concrete wall in the picture. Two 90 degree elbows will be required, one to turn into the interior wall, and one to turn toward the sink.

I have zero access to the vent stack for the soil pipe in the picture. I do have access to a vent pipe for a different soil pipe serving a bathroom in another part of the basement. However it will be a long run, probably 40 - 50 feet. It will be impossible to maintain a constant slope in the horizontal part of the run.

For what it's worth AAVs seem to be legal here.

Comments or recommendations anyone? Any suggestions will be greatly appreciated.
Thank you for any help you may be able to provide.

I'm at another location right now, so no additional pics for several days. I believe I would have noticed any capped off vent lines. though. I looked it over, trying to find one without success.

It is a future rough, intended for a sink installed right next to the soil pipe. AFAIK, that would not have required a vent. Unfortunately, the situation dictates that it be installed in another location.

I would look at the floor layout in the main floor, as the most reliable solution would be to run a vent up through an interior wall into the attic, where it can go through the roof or be connected to an existing vent stack within the attic.

There is no way for me to run a new vent pipe to the attic. I can get to an existing vent pipe (different stack) by running a line up in the basement trusses under the main floor. Its a long run, and there is no way for me to have a constant slope. There are just too many obstacles to deal with.

If a long run is not a problem and a perfect constant slope isn't required, it's doable.

A horizontal run must be pitched for it's entire length without any question. It cannot have any bends or dips that would allow condensation or drain water to collect at any point in the pipe.

I have not yet seen a house without an interior wall in which wire or pipe can be run from basement to attic. It does not have to be at the sink.

Using some patience and careful measuring, up to 2" PVC can fished through a single story 2x4 stud wall without removing any wallboard.
Lathe and plaster is a little tougher to fish through as the walls are full of rough plaster edges, but houses of that era tend to have balloon framing and real 2"x4" studs, so there is room.

An 8' ceiling should not have firestops. That drain may be subjected to both positive and negative pressures since there is a bathroom/toilet above it. An AAV cannot relieve positive pressures. In addition, the vent has to connect close to the sink at the end of that 20' run so it will either be closer or further from that nearest vent.

An 8' ceiling should not have firestops. That drain may be subjected to both positive and negative pressures since there is a bathroom/toilet above it. An AAV cannot relieve positive pressures. In addition, the vent has to connect close to the sink at the end of that 20' run so it will either be closer or further from that nearest vent.

Click to expand...

The main floor above has a nine foot ceiling. There is a firestop in every wall cavity, without exception. The builder always has his framers install them as they go along in order to help prevent wavy walls. I verified the firestops by looking at pictures I took when the house was being framed.

While I was going through the pics, I spotted a vent pipe that comes up from the basement floor in a nearby wall cavity. I believe it must be the vent for the floor drain, which is near where the sink is going. I can probably tie the the sink vent to floor drain vent line.

I had completely forgotten about that particular vent. I think my problem may be solved. Thanks to all who responded.